Fibrinogen, a protein circulating within the blood, plays a fundamental role in the body’s natural defense mechanisms. It is a component that contributes to maintaining blood vessel integrity and responding to injury.
What is Fibrinogen?
Fibrinogen is a soluble protein produced primarily in the liver. It circulates within the blood plasma as a precursor molecule. This large glycoprotein has a complex structure. Its soluble nature allows it to circulate freely, ready to participate in blood clotting when needed.
Fibrinogen’s Role in Blood Clotting
When a blood vessel is injured, the coagulation cascade converts fibrinogen into an insoluble form called fibrin. An enzyme called thrombin acts on fibrinogen, cleaving it to form fibrin monomers. These fibrin monomers then spontaneously link together, forming long, fibrous strands.
These fibrin strands create a mesh-like network at the site of injury. This meshwork effectively traps red blood cells and platelets, forming a stable blood clot. The resulting clot seals the damaged vessel, preventing further blood loss and allowing for wound healing to begin.
Understanding Fibrinogen Levels
Measuring fibrinogen levels provides insights into the body’s clotting ability. A healthy range for fibrinogen in adults is 200 to 400 milligrams per deciliter (mg/dL). Deviations from this range can indicate underlying health conditions.
Elevated fibrinogen levels, or hyperfibrinogenemia, can occur due to various factors. These include inflammation, infections, tissue damage from trauma or surgery, certain chronic diseases, and pregnancy. Smoking is also associated with higher fibrinogen levels. Persistently high levels can increase the risk of thrombosis, the formation of unwanted blood clots.
Conversely, low fibrinogen levels, termed hypofibrinogenemia or afibrinogenemia, can lead to an increased risk of bleeding. Such low levels may be caused by genetic disorders, severe liver disease, or conditions involving excessive consumption of clotting factors, such as disseminated intravascular coagulation (DIC). Significant blood loss or large-volume blood transfusions can also temporarily lower fibrinogen concentrations.
Testing Fibrinogen
Fibrinogen levels are measured through a blood test, typically ordered to investigate bleeding or clotting concerns. Two main types of tests are the fibrinogen activity test and the fibrinogen antigen test. The activity test assesses how well fibrinogen functions in forming a clot, while the antigen test measures the actual amount of the protein present in the blood. A healthcare provider might order these tests as part of a broader coagulation panel to evaluate the overall blood clotting system.